1. Field of the Invention
The present invention generally relates to an illumination device for automobiles and other vehicles, and in particular to an automotive illumination device that controls a state of illumination of an automotive light or a lamp.
2. Description of the Related Art
FIG. 7 illustrates an example of a conventional automotive or vehicle-installed illumination device 1 (known devices of this kind are advocated for example in Japanese Patent Application Laid-Open Publications No. H05-338489 and No. 2001-71812).
The exemplary automotive illumination device 1 incorporates (a) a dome lamp bulb 2, (b) a transistor switch 3, (c) a door status detection unit 5, which serves as a “door status detection unit” in the context of the present invention, (d) a dome switch 6 that allows the dome lamp bulb 2 to be manually turned on and off, the dome switch 6 serving as a “manipulation unit” in the context of the present invention, and (e) a microcontroller 7, which serves as an “illumination control unit” in the context of the present invention.
Operations of the microcontroller 7, which controls overall functionality of the illumination device 1, can be summarized as follows.
When the door status detection unit 5 detects opening of a door of the automobile, the microcontroller 7 controls the transistor switch 3 to turn on the dome lamp bulb 2 of the automobile by gradually making the bulb 2 brighter.
In contrast, when the door status detection unit 5 detects closure of the door, the microcontroller 7 controls the transistor switch 3 and makes the dome lamp bulb 2 gradually dimmer to turn off the dome lamp bulb 2 (see (B) of FIG. 8).
Also, when the dome switch 6 is turned on, the microcontroller 7 closes (turns on) the transistor switch 3 to illuminate the dome lamp bulb 2.
In contrast, when the dome switch 6 is turned off, the microcontroller 7 opens (turns off) the transistor switch 3 to turn off the dome lamp bulb 2.
In recent years, increasing types of automobiles feature a smart entry system that controls locking and unlocking of the door of the automobile without the aid of a mechanical key.
The smart entry system includes an in-vehicle unit 4 and a portable device 8, and locking and unlocking of the door can be controlled by the communications between them.
Specifically, the in-vehicle unit 4 is configured to transmit a request signal to the portable device 8. When the request signal is received by the portable device 8 carried by a user of the automobile approaching the automobile from an outside thereof, then the portable device 8 transmits an answer signal containing an authentication code. When the answer signal is received by the in-vehicle unit 4, the in-vehicle unit 4 checks the received authentication code contained in the answer signal against an authentication code previously stored in the in-vehicle unit or any external memory unit connected thereto. If the authentication is successful, then the door and/or a luggage door of the automobile are locked and unlocked in response to the user's operation of the door handle and/or the luggage door's handle.
In a case of the automobile incorporating such smart entry features, the microcontroller 7 of the automotive illumination device 1 will control the transistor switch 10 to illuminate in a gradual manner a welcome dome lamp 9 provided near the dome lamp when the user carrying the portable device 8 approached the automobile and the authentication was successfully made by the in-vehicle unit 4 (see (A) in FIG. 8). Subsequently, the microcontroller 7 controls the transistor switch 10 to gradually decrease brightness of the welcome dome lamp 9, and finally turns off the lamp 9 when the user opened the door, came in the automobile, closed the door again, and a predetermined period of time has elapsed after closure of the door or when an engine of the automobile has been started after closure of the door (for example, see the Japanese Patent Application Laid-Open Publications No. 2009-1153 and No. 2007-39982).